A question as not clear from the pictures - is the big sprocket a steel one or a worn aluminium one? The latter can give different noises under power/on over-run when worn as most wear occurs on the drive side of the teeth. Also is the hub silver or black annodised...if the former, it will be an early hub that is much harder to get properly aligned and the belt clear of the tyre.
When we change the rear tyre, we have the car up on stands and run the engine for a while to check the alignment is stable.
